📝 STANDARD DESCRIPTION:
Bones of the leg (between stifle and hock).
TIBIA — Ox Standard:
- Main weight-bearing bone of leg.
- Proximal end: Medial & Lateral condyles; Tibial Tuberosity (insertion of patellar ligaments); intercondylar eminence.
- Shaft: Triangular in cross-section.
- Distal end: Cochlea tibiae — has 2 grooves & 2 ridges that fit the talus (forms the hock).
- Medial malleolus (medial bony bump at hock).
FIBULA — Ox Standard:
- Greatly REDUCED.
- Proximal part: small bony nodule fused to lateral condyle of tibia.
- Distal part: small 'Os Malleolare' (lateral malleolus bone) at lateral side of hock — articulates with talus.
- Shaft is ABSENT in ox.
📚 DETAILED DESCRIPTION:
TIBIA — main bone of the leg (crus)
The tibia is a long bone running from the stifle to the hock. It is the major weight-bearing bone of the leg.
PROXIMAL END:
• Medial & Lateral Condyles: Large flat surfaces that meet the femoral condyles at the stifle. Between them lies the intercondylar eminence with attachment for cruciate ligaments and menisci.
• Tibial tuberosity: Cranial bony prominence — the patellar ligaments insert here. Easily palpable below the stifle.
• Extensor groove: Lateral to the tuberosity; holds the tendon of the long digital extensor at its origin.
SHAFT: Triangular in cross-section. Cranial border (the 'shin') is sharp and palpable just under the skin (= tibial crest).
DISTAL END:
• Cochlea tibiae: Pulley-shaped articular surface with 2 ridges and 2 grooves that interlock with the talus → makes the hock a hinge joint.
• Medial Malleolus: Bony bump on the medial side of the hock.
FIBULA in OX:
The fibula is greatly reduced (because the leg only flexes-extends, no twisting needed).
• Proximal — small nodule fused to the lateral condyle of tibia.
• Shaft — ABSENT.
• Distal — represented by a separate small bone called the os malleolare (lateral malleolus bone), which articulates with the talus on the lateral side of the hock.
UG MEMORY: 'Ox fibula = head + tip only, shaft missing'.
// COMPARATIVE ANALYSIS
| HORSE |
Tibia robust. Fibula has SHAFT but only on upper half — fades distally. Lateral malleolus is part of TIBIA. |
| DOG |
Tibia and Fibula BOTH COMPLETE and separate. Both bones contribute to the hock. Allows slight rotation. |
| PIG |
Both tibia and fibula complete and separate (like dog). |
| FOWL |
Tibia fuses with proximal tarsals → TIBIOTARSUS (a single long bone). Fibula present as a thin spike on the lateral side, not full length. |
CLINICAL RELEVANCE
Tibial Crest Fracture: Direct trauma. Avulsion fractures of the tibial tuberosity in young calves at the growth plate.
Hock Injuries: The medial malleolus + os malleolare form the bony pillars of the hock — fractures here cause severe lameness.
